Digital-to-analog conversion unit, driving apparatus and panel display apparatus using the same

Abstract

A digital-to-analog conversion unit, and a driving apparatus and a panel display apparatus using the same are provided. A driving voltage output from the digital-to-analog conversion unit can be a positive polarity voltage or a negative polarity voltage, wherein the driving voltage output from an output buffer is a positive polarity voltage and the driving voltage output from an output inverter is a negative polarity voltage. The apparatus only needs one set of grayscale voltage so that the layout area of the apparatus, and the flicker and the residual images of the display panel can be reduced.

What is claimed is: 
     
         1 . A driving apparatus for use in a display panel, comprising:
 a plurality of output channels for providing a first driving voltage and a second driving voltage;   a data latch unit for outputting multiple M-bit digital data, wherein M is a positive integer;   a grayscale voltage generator for generating 2 M  grayscale voltages, wherein the voltage polarities of the grayscale voltages are the same;   a digital-to-analog conversion unit, coupled to the data latch unit and the grayscale voltage generator, comprising:   a first digital-to-analog converter coupled to the data latch unit and the grayscale voltage generator;   a second digital-to-analog converter coupled to the data latch unit and the grayscale voltage generator;   an output buffer, coupled to the first digital-to-analog converter, for outputting the first driving voltage; and   an output inverter, coupled to the second digital-to-analog converter, for outputting the second driving voltage;   a switch device, coupled to the digital-to-analog conversion unit, for switching the first driving voltage and the second driving voltage to the paths of the output channels, wherein if the output channel provides the first driving voltage in a frame period, the output channel provides the second driving voltage in the next frame period.   
     
     
         2 . The driving apparatus of  claim 1 , wherein the switch device comprises:
 a first switch having a first terminal coupled to the output buffer and a second terminal coupled to the output inverter, wherein in a first time period, the first terminal and a third terminal of the first switch are conducted, and in a second time period, the second terminal and the third terminal of the first switch are conducted; and   a second switch having a first terminal coupled to the output inverter and a second terminal coupled to the output buffer, wherein in the first time period, the first terminal and a third terminal of the second switch are conducted, and in the second time period, the second terminal and the third terminal of the second switch are conducted.   
     
     
         3 . The driving apparatus of  claim 1 , wherein the output inverter comprises:
 a first resistor;   a first amplifier having a first input terminal coupled to a second terminal of the first resistor, and a second input terminal of the first amplifier coupled to the ground;   a second resistor having a first terminal coupled to the first input terminal of the first amplifier, and a second terminal coupled to an output of the first amplifier; and   a second amplifier having a first input terminal electrically connected to an output of the second amplifier, and a second input terminal coupled to the output of the first amplifier.   
     
     
         4 . The driving apparatus of  claim 1 , wherein the output inverter comprises:
 a third resistor;   a third amplifier having a first input terminal coupled to a second terminal of the third resistor;   a fourth resistor having a first terminal coupled to the first input terminal of the third amplifier, and a second terminal coupled to an output of the third amplifier;   a fifth resistor having a second terminal coupled to a second input terminal of the third amplifier;   a variable resistor having a first terminal coupled to the second terminal of the fifth resistor;   a sixth resistor having a first terminal coupled to a second terminal of the variable resistor; and   a fourth amplifier having a first input terminal electrically connected to an output of the fourth amplifier, and a second input terminal coupled to the output of the third amplifier.   
     
     
         5 . The driving apparatus of  claim 1 , wherein the voltage polarities of the first driving voltage and the second driving voltage are opposite. 
     
     
         6 . The driving apparatus of  claim 1 , wherein the first driving voltage is a positive polarity voltage, and the second driving voltage is a negative polarity voltage. 
     
     
         7 . The driving apparatus of  claim 1 , wherein the voltage polarities of the first driving voltage and the second driving voltage are determined depending on a common voltage. 
     
     
         8 . The driving apparatus of  claim 7 , wherein the common voltage is a ground level. 
     
     
         9 . The driving apparatus of  claim 7 , wherein the output buffer operates between the common voltage and a first voltage, and the output inverter operates between a second voltage and the common voltage. 
     
     
         10 . The driving apparatus of  claim 9 , wherein the first voltage is a positive voltage, the second voltage is a negative voltage, and the absolute values of the first voltage and the second voltage are equal. 
     
     
         11 . A digital-to-analog conversion unit, comprising:
 2N digital-to-analog converters, wherein N is a positive integer;   N output buffers having the (i) th  output buffer coupled to the (2i−1) th  digital-to-analog converter, wherein i is an integer and 1≦i≦N, and each of the output buffers individually outputs a first driving voltage; and   N output inverters having the (i) th  output inverter coupled to the (2i) th  digital-to-analog converter, wherein each of the output inverters individually outputs a second driving voltage;   wherein the voltage polarities of the first driving voltage and the second driving voltage are opposite.   
     
     
         12 . The digital-to-analog conversion unit as claimed in  claim 11 , wherein each of the output inverters comprises:
 a first resistor;   a first amplifier having a first input terminal coupled to a second terminal of the first resistor, and a second input terminal coupled to the ground;   a second resistor having a first terminal coupled to the first input terminal of the first amplifier, and a second terminal coupled to an output of the first amplifier; and   a second amplifier having a first input terminal electrically connected to an output of the second amplifier, and a second input terminal coupled to the output of the first amplifier.   
     
     
         13 . The digital-to-analog conversion unit as claimed in  claim 11 , wherein each of the output inverters comprises:
 a third resistor;   a third amplifier having a first input terminal coupled to a second terminal of the third resistor;   a fourth resistor having a first terminal coupled to the first input terminal of the third amplifier, and a second terminal coupled to an output of the third amplifier;   a fifth resistor having a second terminal coupled to a second input terminal of the third amplifier;   a variable resistor having a first terminal coupled to the second terminal of the fifth resistor;   a sixth resistor having a first terminal coupled to a second terminal of the variable resistor; and   a fourth amplifier having a first input terminal electrically connected to an output of the fourth amplifier, and a second input terminal coupled to the output of the third amplifier.   
     
     
         14 . The digital-to-analog conversion unit as claimed in  claim 11 , wherein the first driving voltage is a positive polarity voltage, and the second driving voltage is a negative polarity voltage. 
     
     
         15 . The digital-to-analog conversion unit as claimed in  claim 11 , wherein the voltage polarities of the first driving voltage and the second driving voltage are determined depending on a common voltage. 
     
     
         16 . The digital-to-analog conversion unit as claimed in  claim 15 , wherein the common voltage is a ground level. 
     
     
         17 . The digital-to-analog conversion unit as claimed in  claim 15 , wherein the output buffers operate between the common voltage and a first voltage, and the output inverters operate between a second voltage and the common voltage. 
     
     
         18 . The digital-to-analog conversion unit as claimed in  claim 17 , wherein the first voltage is a positive voltage, the second voltage is a negative voltage, and the absolute values of the first voltage and the second voltage are equal. 
     
     
         19 . A panel display apparatus, comprising:
 a display panel;   a gate driving circuit, electrically connected to the display panel, for outputting at least a scan signal; and   a driving apparatus, electrically connected to the display panel through multiple output channels, for providing at least a first driving voltage and a second driving voltage through the output channels in accordance with the scan signal, wherein the driving apparatus comprises:   a grayscale voltage generator for generating multiple grayscale voltages with the same voltage polarity; and   a digital-to-analog conversion unit, coupled to the grayscale voltage generator, for determining whether or not to inverse the grayscale voltages according to the digital data received by the digital-to-analog conversion unit, and further at least providing the first driving voltage and the second driving voltage, wherein the voltage polarities of the first driving voltage and the second driving voltage are opposite; and   a switch device, coupled to the digital-to-analog conversion unit, for switching the first driving voltage and the second driving voltage to the paths of the output channels, wherein, if the output channel provides the first driving voltage in a frame period, the output channel provides the second driving voltage in the next frame period.   
     
     
         20 . The panel display apparatus as claimed in  claim 19 , wherein the digital-to-analog conversion unit comprises:
 a first digital-to-analog converter electrically coupled to the grayscale voltage generator;   a second digital-to-analog converter electrically coupled to the grayscale voltage generator;   an output buffer, coupled to the first digital-to-analog converter, for outputting the first driving voltage; and   an output inverter, coupled to the second digital-to-analog converter, for outputting the second driving voltage.   
     
     
         21 . The panel display apparatus as claimed in  claim 20 , wherein the switch device comprises:
 a first switch, having a first terminal coupled to the output buffer, and a second terminal coupled to the output inverter, wherein, in a first time period, the first terminal and a third terminal of the first switch are conducted, and in a second time period, the second terminal and the third terminal of the first switch are conducted; and   a second switch having a first terminal coupled to the output inverter, and a second terminal coupled to the output buffer, wherein, in the first time period, the first terminal and a third terminal of the second switch are conducted, and in the second time period, the second terminal and the third terminal of the second switch are conducted.   
     
     
         22 . The panel display apparatus as claimed in  claim 19 , wherein the first driving voltage is a positive polarity voltage, and the second driving voltage is a negative polarity voltage. 
     
     
         23 . The panel display apparatus as claimed in  claim 19 , wherein the voltage polarities of the first driving voltage and the second driving voltage are determined depending on a common voltage. 
     
     
         24 . The panel display apparatus as claimed in  claim 23 , wherein the common voltage is a ground level.